A small EJB problem in the NamingContextFactory

I started to use JBoss from last week onwards and i was successful enough to deploy my first Session Bean in the JBoss4 Server with out any errors. But when i tried to write the client application, i was not successful as the deployment. the file compiles correctly withone any warnings and errors but when i try to run the application it gives a small error.

First let me tell abt the bean i wrote . it is a small bean that returns a string value and it is similar to the normal HelloWorld applications. The deployed jar has got the 3 needed class files and the ejb-jar.xml file.